The echo (reflected sounD. will be distinctly heard only at ordinary temperatures if the distance of the reflecting surfaces from the source of sound is at least ________...?
(A) 1120 ft
(B) 120 ft
(C) 56 ft
(D) 100 ft
56 ft
Comments
The echo (reflected sounD. will be distinctly heard only at ordinary temperatures if the distance of the reflecting surfaces from the source of sound is at least ________...?
When a ray of sunlight enters a dark room , its straight path become visible because of dust particles hanging in the air. It is because light is _________...?
(A) Visible
(B) Transparent
(C) Invisible
(D) opaque
Visible
Comments
When a ray of sunlight enters a dark room , its straight path become visible because of dust particles hanging in the air. It is because light is _________...?